Putthe slideunderthemicroscopeand observeunderlow power first,and
thenunderhigh power.
You will observe: Large brick-shapedcellscontainingsmall, oval green
bodies.
Elodea,like allotherlivingplants,is madeup of living cells. Inaddition
to protoplasmand a nucleus, the cellsofgreenplantscontaingreen bodies
called chloroplasts. In turn, chloroplasts contain a green substance called
chlorophyll. Greenplants,bothwater-livingandland-living,are able tomanu-
facture their own food because they contain this valuable life-supporting
chemical,chlorophyll.
Greenplantsare theoriginalsourceofallourfood. Theyprovidefood
directlyfor us and indirectly,too,because theyprovidefood for theanimals
we eat. Itis thechlorophyllin greenplantsthatmakespossible awonderful
process called photosynthesis,which you willlearnmoreabouton page 37.
Bear in mindthatall lifedependson this greenchemical-chlorophyll.OBSERVING CELLS OF THE HUMAN BODY- CHEEK-LINING CELLS
Materials: A flat-ended toothpick, a pipetteor medicinedropperand a
dilute iodinesolution.
Follow this procedure: Using the medicine dropper or pipette, place a
dropofiodinesolutionin the middleofa clean glass slide.
Gentlyscrape the inside liningofyourcheek with the flat endofa clean
toothpick. Putthe scrapings in thedropofiodinesolutionon the slide.
Observe first under low power, and then under high power ofyour
microscope.
Youwillobserve:Small cells, some folded and some flat,scatteredeither
by themselves or ingroupsin themicroscopefield. The nucleus, ororganizing
mechanism,ofeach cell willappearas a smallbrownspotin the middle.